The first week immediately after the birth of a calf is very crucial to the continued health of a mother cow and subsequent reproduction success. Up to 90% of dairy cows have bacterial contamination of the uterus in the first week post-partum. Normally, postpartum cows remove bacteria within six weeks by natural processes. However, complications such as sustained uterine infection, reproductive tract inflammation, or retained placenta can have a major impact on milk production or subsequent reproduction. Such complications and their effects can occur quite frequently. The risk of one type of reproductive tract inflammation, metritis, is around 22% in a typical herd. Predisposing factors are dystocia and retained fetal membranes, as well as deficiencies in hygiene and metabolic imbalances around parturition.
Metritis is probably the most economically important postpartum disorder in dairy cattle, causing high economic losses due to prolonged days open and involuntary culling. Metritis can result in an increase of open days (33 days), lower milk yield (typical loss of $83 per cow), and a decrease in pregnancy from a 17.5% normal rate to 13% with metritis. Together, these contribute to an average estimated annual cost of about $380 per cow. For a typical 1000-cow herd in 2008, metritis is estimated as costing $79,000 in losses due to milk loss, culling risk, and reproductive changes (Overton, M. and Fetrow J. Proceedings of the 2008 Dairy Cattle Reproduction Council Convention, Nov. 7-8, 2008, Omaha, Nebr.).
Metritis is an inflammation of the uterus and is often associated with malodorous watery uterine discharge and high (˜103° F.) fever. Among other factors, infection with a number of infectious microorganisms plays a role in postpartum metritis. Metritis can present clinically or subclinically. Both clinical and subclinical metritis can have effects on milk production and fertility and, therefore, need to be avoided if possible.
For the farmer, there is a dilemma whether or not to treat cows for possible metritis. A variety of treatment therapies are available with varying success rates and varying costs associated with them. Intrauterine antibiotic therapy is one method. One of the most common antibiotics used is oxytetracycline. However, oxytetracycline treatment shows only limited efficacy and results in antibiotic residues appearing in milk. Prostaglandin (PGF) therapy shows some efficacy but is not economical. Iodine infusion is relatively inexpensive but can adversely affect subsequent reproduction. As such, all of these treatments have issues associated with them.
Successful cleansing of the postpartum cow is a major key to subsequent reproductive status and milk production. The lining of the postpartum uterus is in constant contact with fluid and tissue debris. This fluid and tissue debris can lead to growth with a variety of bacteria and other microorganisms. Whether or not infection develops in the uterus depends on the types of bacteria present and the condition of uterus. The uterus acts as an incubator as far as encouraging the rapid growth and increase in bacteria. The multiplication of bacteria is enhanced by sections of placenta that may cling to the uterine lining after calving. These fragments, sometimes small and sometimes quite large, may resist dislodgement by virtue of various cotyledons that have not released themselves. Cotyledons are button-like attachments that serve as the means for supplying nutrients from the mother cow to the fetus within the uterus. Before birth, the cotyledons range from 80 to 120 in number. In typical circumstances, most cotyledons dislodge during parturition. It is only those that do not release that prove troublesome, as they may retain sections of the placenta. When pieces of attached placenta remain in the uterus, they can lead to infections that can result in metritis. This can have a significant impact on the health of the postpartum cow.
Previous methods for removing dead tissue from the uterus of dairy cows have used liquid hydrogen peroxide. See U.S. Pat. No. 3,903,265. Such methods, however, are difficult to perform properly and can be applied only under specific physiological conditions.